To use the Evo with an external power amplifier, connect from the 'Pre-Out' on the Evo, and using an RCA cable connect to the RCA Input on your amplifier. Please see below an example of this configuration using the Edge W Power Amplifier.
IMPORTANT: If the amplifier you intend to use with the Evo has a Balanced/Unbalanced switch, please ensure that this is set to Unbalanced.